A rotary phase converter for connection to a single-phase a.c. power source and adapted to supply polyphase current to a polyphase electrical load. The converter includes a dynamoelectric machine having at least three stator windings and at least first, second and third output terminals, an autotransformer...http://www.google.com/patents/US4249237?utm_source=gb-gplus-sharePatent US4249237 - Rotary phase converter
